1955 Johnson Qd-16 Carb Adjustments

[Jay1087]

On my QD-16 10hp outboard the carb adjustments move freely. How do i fix this and what is the position that they are supposed to be in? Any information would be helpful.

 

[F_R]

Re: 1955 Johnson Qd-16 Carb Adjustments

There are two soft packing washers behind each of the brass nuts around the needle valves. Tighten the nuts enough to make the needles stiff to turn. If the desired results cannot be obtained, you will have to put in new packing washers.

If you can get it started, don't worry about preliminary settings which are 3/4 turn from lightly seated for the high speed (lower) needle and 1 1/2 turn for the slow speed (upper) needle. Final adjustment has to be done on a boat in the water. Simply set the high speed to where it runs the best at wide open throttle and then slow it down to idle and do the same with the slow speed needle. Then reinstall the knobs at mid scale. Then forget about them unless a minor adjustment is necessary due to extreme temperature or altitude change.

 

[Joe Reeves]

Re: 1955 Johnson Qd-16 Carb Adjustments

(Carburetor Adjustments - Two Adjustable N/Vs)
(J. Reeves)

Initial settings are: Bottom high speed = seat gently, then open 1 turn out. Top slow speed = seat gently, then open 1-1/2 turns.

Setting the high and low needle valves properly:

NOTE: For engines that DO NOT have a shift selection, obviously there is no NEUTRAL position. Simply lower the rpms to the lowest setting to obtain the low speed needle valve adjustment.

(High Speed) Start engine (it will run pretty rough), shift into forward gear, take up to full throttle. In segments of 1/8 turn, waiting for the engine to respond between turns, start turning in the bottom high speed needle valve. You'll reach a point whereas the engine will either start to die out or spit back (sounds like a mild backfire). At that point, back out the needle valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest setting.

(Low Speed) Slow the engine down to where it just stays running. Shift into neutral. Again in segments of 1/8 turns, start to turn the top needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running. Eventually you'll hit the point where the engine wants to die out or it will spit back. Again, at that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

When you have finished the above adjustments, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

When time permits, visit my store (copy/paste) at: stores.ebay.com/Evinrude-Johnson-Outboard-Parts-etc?refid=store